With the increasing sophistication and use of electrical and electronic equipment in recent years, electro-magnetic interference (EMI) has been increased, and electromagnetic waves are generated even from a display such as a cathode ray tube (CRT) and a plasma display panel (PDP). Plasma display panels are an assembly of a glass having a data electrode and a fluorescent layer, and a glass having a transparent electrode. When powered on, they generate a large quantity of electromagnetic waves and near-infrared rays.
In the description of the present invention, the term “electromagnetic waves” is used in referring to electromagnetic waves with frequencies below the frequency range of approximately MHz to GHz, and is distinguished from infrared rays, visible rays and ultraviolet rays.
Near-infrared rays generated from the front surface of a plasma display in the wavelength range from 800 to 1,100 nm can cause other devices such as VTR to malfunction; therefore, it is demanded to shield such rays. In general, a near-infrared absorbing filter (optical filter) having a function of absorbing near-infrared rays is provided on the observer-side surface of a PDP to shield near-infrared rays generated.
The near-infrared absorbing filter normally comprises a near-infrared absorbing, pressure-sensitive adhesive layer. This layer comprises a near-infrared absorbing agent having a near-infrared absorption function and a pressure-sensitive adhesive having a pressure-sensitive adhesive function for bonding the filter to the body or front panel of a display. Adhesives comprising organic near-infrared absorbing agents (dyes) have been studied for use as the near-infrared absorbing, pressure-sensitive adhesive (Patent Literature 1).    Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2005-272588    Patent Literature 2: JP-A No. 2002-311843    Patent Literature 3: JP-A No. 2006-154516    Patent Literature 4: JP-A No. 2007-095971